JP2018135854A - Control device of cooling device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To raise a temperature of cooling water in a cylinder block 12 as early as possible.SOLUTION: An CPU 62 stops a main water pump 21 on the condition that a water temperature THWe is equal to or lower than a prescribed temperature Tth. The CPU 62 drives a sub water pump 36 when the water temperature THWe is equal to or lower than the prescribed temperature Tth, and determines the presence/absence of opening fixation abnormality of a thermostat 26 on the basis of the difference between a rise speed of a water temperature THWx in opening of a selector valve 38 and a rise speed of the water temperature THWx in closing of the selector valve 38.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a control device for a cooling device applied to a cooling device for an internal combustion engine.

  For example, the following Patent Document 1 discloses a main pump (main water) that circulates cooling water in a loop path formed by an inner passage that is a cooling water passage in a cylinder block and a cylinder head and an outer passage outside thereof. In addition to the pump), a sub-pump (sub-water pump) is described. Here, the sub-water pump circulates the cooling water in the short loop path between the cylinder head and the heater without passing through the cylinder block. Further, this document describes that when the internal combustion engine is cold, the main water pump is driven and the sub-water pump is stopped (FIG. 4).

JP 2012-241557 A

  By the way, as described above, when the main water pump is driven in the cold state, the cooling water in the cylinder block and the cylinder head circulates in the loop path.

  In order to solve the above problems, a main loop path which is a cooling water path provided with a main water pump and penetrating the cylinder block and the cylinder head, and an exhaust heat recovery device, a heater and a sub water pump outside the internal combustion engine are provided. And a sub-loop path that is a path of the cooling water provided. The main loop path passes through a radiator and a thermostat outside the internal combustion engine, and the radiator and the thermostat. Branching to a second path that includes a part of the sub-loop path, and the sub-loop path bypasses the heater and includes the sub-water pump and the exhaust heat recovery device. Is provided as a closed loop, and the detour path includes the detour path. A stop valve that stops the main water pump on the condition that the temperature of the internal combustion engine is equal to or lower than a predetermined temperature, and the temperature of the internal combustion engine is equal to or lower than the predetermined temperature. When the sub-water pump is in a driving state, a difference between a rising rate of the temperature of the cooling water in the closed state of the switching valve and a rising rate of the temperature of the cooling water in the opened state of the switching valve, and a threshold value And a determination process for determining whether or not there is an abnormality in the open adhesion of the thermostat.

  In the above configuration, the internal combustion engine can be warmed up as soon as possible in order to bring the main water pump into the stopped state by the stop process on condition that the temperature of the internal combustion engine is equal to or lower than the predetermined temperature.

  However, in that case, even if there is an open sticking abnormality in the thermostat during the stop process, the presence or absence of the open sticking abnormality is determined based on the difference in temperature rise rate between when the thermostat is open and normal. It is difficult to do. Here, when driving the sub-water pump, if there is an open fixing abnormality in the thermostat, a certain amount of cooling water can be circulated to the radiator via the thermostat by the flow of the cooling water caused by the sub-water pump. However, there is a possibility that the temperature increase rate of the cooling water caused by the abnormal opening and fixing of the thermostat is difficult to distinguish from the influence of disturbances other than the abnormal opening and fixing. Therefore, in the above configuration, attention is paid to the difference between the rising speed of the temperature of the cooling water when the switching valve is closed and the rising speed when the switching valve is open. Since this difference includes the effect of the presence or absence of an open fixing abnormality of the thermostat, the presence or absence of an abnormality of the thermostat can be determined by determining this difference by comparing the difference with a threshold value.

The block diagram of the control apparatus and cooling device concerning one Embodiment. The flowchart which shows the procedure of the process regarding the abnormality diagnosis concerning the embodiment. (A) And (b) is a time chart explaining the principle of the abnormality diagnosis concerning the embodiment. The time chart explaining the subject which the embodiment solves. (A) And (b) is a time chart explaining the subject which the embodiment solves.

  Hereinafter, an embodiment of a control device for a cooling device will be described with reference to the drawings.

  An internal combustion engine 10 shown in FIG. 1 includes a cylinder block 12 and a cylinder head 14. An inner passage 16 that is a passage for cooling water is formed in the cylinder block 12, and inner passages 17, 18, and 19 that are passages for cooling water are connected to the cylinder head 14. The inner passages 17, 18, 19 are connected to the inner passage 16.

  An outer passage 20 is connected to the inner passage 16, and an outer passage 22 is connected to the inner passage 19. An electric main water pump 21 is provided in the outer passage 20, and a radiator 24 and a thermostat 26 are provided in the outer passage 22. A loop path is formed by the outer passage 20, the inner passages 16 and 19, and the outer passage 22.

  An outer passage 30 is connected to the inner passage 17, and an exhaust heat recovery device 32 that recovers the heat of the exhaust gas of the internal combustion engine 10 into cooling water is provided in the outer passage 30. A loop path is formed by the outer passage 20, the inner passages 16, 17, and the outer passage 30.

  An outer passage 34 is connected to the outer passage 30, and an electric sub-water pump 36 and a heater 39 are provided in the outer passage 34. The outer passages 30 and 34 form a loop path that passes through the sub-water pump 36, the heater 39, and the exhaust heat recovery device 32.

  Further, a bypass path 37 that bypasses the heater 39 is connected to the outer passages 30 and 34. The bypass path 37 is provided with an electronically controlled switching valve 38 that opens and closes the bypass path 37.

  An outer passage 40 is connected to the inner passage 18, and an EGR cooler 42 is provided in the outer passage 40. The outer passage 40 is connected to the outer passage 30. Thus, a loop path that passes through the EGR cooler 42 and the exhaust heat recovery device 32 is formed by the inner passages 17 and 18 and the outer passages 40 and 30.

  An outer passage 44 is connected to the outer passage 30. The outer passage 44 is provided with an EGR valve 46 and a throttle body 48. The outer passages 30 and 44 form a loop path that passes through the vicinity of the EGR valve 46 and the throttle body 48 and the exhaust heat recovery device 32.

  The control device 60 operates the main water pump 21, the sub water pump 36, and the switching valve 38 in order to control the temperature of the cooling water as a control amount of the internal combustion engine 10. At this time, the controller 60 detects the temperature of the cooling water on the outlet EX side to the outer passage 22 detected by the temperature sensor 50 (water temperature THWe), and the cooling water in the exhaust heat recovery device 32 detected by the temperature sensor 52. Temperature (water temperature THWx). The control device 60 includes a CPU 62, a ROM 64, and an electrically rewritable nonvolatile memory 66. And the control apparatus 60 controls the temperature of a cooling water, when CPU62 runs the program memorize | stored in ROM64.

  Even after the internal combustion engine 10 is started by inputting the IG signal, the CPU 62 stops the main water pump 21 on the condition that the water temperature THWe is equal to or lower than the predetermined temperature Tth. This is intended to promote warm-up of the internal combustion engine 10. The CPU 62 drives only the sub-water pump 36 when the warm-up request of the devices such as the heater 39, the EGR cooler 42, the EGR valve 46, the throttle body 48, etc. occurs while the main water pump 21 is stopped. Can be secured, only the sub-water pump 36 is driven. Note that the CPU 62 drives the main water pump 21 when the difference between the water temperature THWx and the water temperature THWe exceeds a specified value even if the water temperature THWe is equal to or lower than the predetermined temperature Tth. This is to prevent the occurrence of a hunting phenomenon in which the thermostat 26 repeats the valve opening state and the valve closing state when the water temperature THWe exceeds the predetermined temperature Tth and reaches the valve opening temperature of the thermostat 26. It is. That is, if the water temperature THWx is excessively lower than the water temperature THWe when the water temperature THWe exceeds the predetermined temperature Tth and the driving of the main water pump 21 is started, then, after reaching the valve opening temperature of the thermostat 26 In this case, the temperature of the cooling water flowing into the thermostat 26 may increase and then decrease. As a result, the hunting phenomenon of the thermostat 26 may occur. The process of driving the main water pump 21 when the difference between the water temperature THWx and the water temperature THWe exceeds a specified value tends to result in intermittent driving of the main water pump 21 in the process of increasing the water temperature THWe.

  Further, the CPU 62 normally closes the switching valve 38, but if the sub-water pump 36 is abnormal, the CPU 62 opens the switching valve 38. This is because by driving the main water pump 21, the high-temperature cooling water received by the exhaust heat recovery device 32 is passed through the heater 39 via the bypass path 37 having a pressure loss smaller than that of the sub-water pump 36. It is for giving heat to. Further, the CPU 62 uses the switching valve 38 for the determination process of the open adhesion abnormality of the thermostat 26.

  FIG. 2 shows the procedure of the process relating to the determination. The processing shown in FIG. 2 is realized by the CPU 62 repeatedly executing the program stored in the ROM 64 at a predetermined cycle, for example.

  In the series of processes shown in FIG. 2, the CPU 62 first determines whether or not there is a request for executing an open-fixation abnormality diagnosis of the thermostat 26 by opening / closing the switching valve 38 (S10). Here, the conditions for determining that there is an execution request are the conditions that the water temperature THWe is equal to or lower than the predetermined temperature Tth, and the fact that the diagnosis process of the open fixing abnormality of the thermostat 26 has not yet been executed after the internal combustion engine 10 is started. And the condition that the sub-water pump 36 is normal is included. When determining that there is an execution request (S10: YES), the CPU 62 drives the sub-water pump 36 (S12). If the sub-water pump 36 has already been driven in response to a warm-up request for the heater 39 etc., the process of S12 is a process for continuing the drive.

  Next, the CPU 62 measures the increase amount ΔTc of the water temperature THWx during a predetermined period (S14). This process is a process of measuring the rising speed of the water temperature THWx when the switching valve 38 is in the closed state. Next, the CPU 62 opens the switching valve 38 (S16). Then, the CPU 62 measures the increase amount ΔTo of the water temperature THWx during a predetermined period (S18). This process is a process of measuring the rising speed of the water temperature THWx when the switching valve 38 is in the open state. When the process of S18 is completed, the CPU 62 returns the switching valve 38 to the closed state (S20).

  Next, the CPU 62 determines whether or not a value obtained by subtracting the increase amount ΔTc measured in the process of S14 from the increase amount ΔTo measured in the process of S18 is smaller than the threshold value Δth (S22). This process is a process for determining whether or not an open fixing abnormality of the thermostat 26 has occurred.

  FIG. 3 (a) shows the transition of the water temperature THWx when the switching valve 38 is in the open state when the thermostat 26 is not open and stuck abnormally as a curve fo, and the switching valve 38 is in the closed state. The transition of the water temperature THWx at the time of is shown by a curve fc. Time t1 is the start timing of the internal combustion engine 10. As shown in FIG. 3A, when the switching valve 38 is in the open state, the water temperature THWx rises earlier than in the closed state. This is because most of the cooling water discharged from the sub-water pump 36 passes through the detour path 37 and the exhaust heat recovery device 32 when the switching valve 38 is in the open state. It is because it will be inhaled. That is, in this case, since the flow rate of the cooling water passing through the heater 39 is small compared with the case where the switching valve 38 is opened, the cooling water received by the exhaust heat recovery device 32 is reduced in the heater 39. This is because the amount of heat radiation is reduced.

  FIG. 3 (b) shows a transition of the water temperature THWx when the switching valve 38 is in the open state when the thermostat 26 is in an open fixing abnormality, as shown by a curve fo, and the switching valve 38 is in the closed state. The transition of the water temperature THWx at the time of is shown by a curve fc. As shown in FIG. 3 (b), even when the thermostat 26 is stuck open, when the switching valve 38 is in the open state, the water temperature THWx is earlier than in the closed state. To rise. However, when the open fixing abnormality of the thermostat 26 occurs, the water temperature THWx both when the switching valve 38 is in the open state and when it is in the closed state, as compared with the case where no abnormality has occurred. As a result, the difference in the rising speed of the water temperature THWx between when the switching valve 38 is open and when it is closed is small.

  In the process of S22 of FIG. 2, paying attention to the property shown in FIG. Note that the threshold value Δth is set based on the upper limit value of the above difference in the rising speed of the water temperature THWx when the open fixing abnormality occurs.

When determining that the CPU 62 is smaller than the threshold value Δth (S22: YES), the CPU 62 determines that an open fixing abnormality of the thermostat 26 has occurred (S24). The CPU 62 operates the warning lamp 70 shown in FIG. 1 to notify the user that an abnormality has occurred, and stores the content of the abnormality in the nonvolatile memory 66.
When the process of S24 is completed or when a negative determination is made in the processes of S10 and S22, the CPU 62 once ends the series of processes shown in FIG.
Here, the operation of the present embodiment will be described.

  After the internal combustion engine 10 is started, the CPU 62 maintains the main water pump 21 in a stopped state on condition that the water temperature THWe is equal to or lower than the predetermined temperature Tth. For this reason, even if the thermostat 26 has an open sticking abnormality, it is difficult to detect this from the behavior of the water temperature THWe.

  A curve fpn indicated by a solid line in FIG. 4 shows an example of an increase in the water temperature THWe in the comparative example in which the main water pump 21 is driven even if the water temperature THWe is equal to or lower than the predetermined temperature Tth, when the thermostat 26 does not have an open fixing abnormality. Show. A curve fpu indicated by a two-dot chain line shows an example of an increase in the water temperature THWe when the thermostat 26 has an open fixing abnormality in the comparative example in which the main water pump 21 is driven even when the water temperature THWe is equal to or lower than the predetermined temperature Tth. Indicates. Time t1 is the start timing of the internal combustion engine 10. As shown in FIG. 4, there is a clear difference between the curve fpn and the curve fpu. This is because, when the thermostat 26 is in an open-fixing abnormality in the process of increasing the water temperature THWe as the warm-up of the internal combustion engine 10 progresses, the cooling water circulating in the internal combustion engine 10 is cooled by the radiator 24. This is because the rate of increase in the water temperature THWe is remarkably slow because of cooling.

  On the other hand, in the present embodiment in which the main water pump 21 is stopped on the condition that the water temperature THWe is equal to or lower than the predetermined temperature Tth, the water temperature THWe is different depending on whether the thermostat 26 has an open fixing abnormality or not. Since it is difficult for the difference in the rising speed to occur, it is difficult to determine whether the thermostat 26 has an open fixing abnormality from the rising speed of the water temperature THWe.

  Here, the CPU 62 drives the sub-water pump 36 when the water temperature THWe is equal to or lower than the predetermined temperature Tth. As a result, when the open fixing abnormality of the thermostat 26 has occurred, a certain amount of cooling water flows back to the internal combustion engine 10 via the outer passage 22, so that the rising speed of the water temperature THWe or the water temperature THWx is controlled by the thermostat. 26 is lower than normal. However, for example, it is difficult to determine the presence / absence of the open sticking abnormality only from the rising speed of the water temperature THWe. This is because the fluctuation amount of the rising speed due to the presence / absence of the open fixing abnormality of the thermostat 26 is not so large, and it is difficult to distinguish it from other factors.

FIG. 5A shows an example of an increase in the water temperature THWx of the present embodiment when the thermostat 26 is normal. Specifically, the solid line shows an example of the rise of the water temperature THWx when the main water pump 21 is always stopped, and the main line is temporarily changed by the alternate long and short dash line when the difference between the water temperatures THWe and THWx exceeds a specified value. An example of increasing the water temperature THWx when a process for driving the water pump 21 is turned on will be described. FIG. 5B shows an example of an increase in the water temperature THWx according to this embodiment when the thermostat 26 is abnormally stuck open. Specifically, the solid line shows an example of the rise of the water temperature THWx when the main water pump 21 is always stopped, and the main line is temporarily changed by the alternate long and short dash line when the difference between the water temperatures THWe and THWx exceeds a specified value. An example of increasing the water temperature THWx when a process for driving the water pump 21 is turned on will be described.
As shown in FIG. 5, it is difficult to distinguish the difference in the rising speed of the water temperature THWx depending on whether or not the thermostat 26 is open and stuck abnormally from other factors.

On the other hand, in the present embodiment, by using the difference between the amount of increase ΔTc in the closed state of the switching valve 38 and the amount of increase ΔTo in the opened state, the determination accuracy of the presence / absence of the open fixing abnormality of the thermostat 26 is improved. Can do.
According to the embodiment described above, the following effects can be obtained.

(1) Even when the water temperature THWe is equal to or lower than the predetermined temperature Tth, the main water pump 21 is driven by the difference between the water temperatures THWe and THWx being increased. In this case, only by measuring the rising speed of the water temperature THWe while the state of the switching valve 38 is fixed, the accuracy in determining whether or not the thermostat 26 is abnormally stuck open is lowered. Therefore, the amount of increase in the closed state of the switching valve 38. The advantage of using the difference between ΔTc and the amount of increase ΔTo in the valve open state is particularly great.
<Correspondence>

The correspondence relationship between the items in the above embodiment and the items described in the column “Means for Solving the Problems” is as follows. The main loop path corresponds to a loop path constituted by the outer passage 20, the inner passages 16, 19 and the outer passage 22, and a loop path constituted by the outer passage 20, the inner passages 16, 17 and the outer passage 30. The sub-loop path corresponds to the path formed by the outer passages 30 and 34. The first path corresponds to a path constituted by the outer path 20, the inner paths 16, 19 and the outer path 22, and the second path is a path formed by the outer path 20, the inner paths 16, 17 and the outer path 30. Corresponding to The stop process is a process that is a condition for the affirmative determination of the process of S10 in FIG. 2 and corresponds to the process executed by the CPU 62, and the determination process corresponds to the process of S22.
<Other embodiments>
In addition, you may change at least 1 of each matter of the said embodiment as follows.

  In the above configuration, the increase amounts ΔTc and ΔTo are quantified using the water temperature THWx. However, the present invention is not limited to this, and for example, the water temperature THWe may be used. Even in this case, if the effect of the presence or absence of abnormal sticking of the thermostat 26 appears in the difference in the rising speed of the water temperature THWe between the closed state and the opened state of the switching valve 38, the difference in the rising speed is used. Thus, it can be determined whether or not the thermostat 26 has an open sticking abnormality.

  The control device is not limited to the one that includes the CPU 62 and the ROM 64 and executes software processing. For example, a dedicated hardware circuit (for example, an ASIC) that performs hardware processing on at least a part of the software processed in the above embodiment may be provided.

  DESCRIPTION OF SYMBOLS 10 ... Internal combustion engine, 12 ... Cylinder block, 14 ... Cylinder head, 16, 17, 18, 19 ... Inner passage, 20 ... Outer passage, 21 ... Main water pump, 22 ... Outer passage, 24 ... Radiator, 26 ... Thermostat, DESCRIPTION OF SYMBOLS 30 ... Outer passage, 32 ... Waste heat recovery device, 34 ... Outer passage, 36 ... Sub-water pump, 37 ... Detour route, 38 ... Switching valve, 39 ... Heater, 40 ... Outer passage, 42 ... EGR cooler, 44 ... Outer Passage, 46 ... EGR valve, 48 ... throttle body, 60 ... control device, 62 ... CPU, 64 ... ROM, 66 ... nonvolatile memory, 70 ... warning light.

Claims (1)

A main loop path, which is a path of cooling water provided with a main water pump and penetrating the cylinder block and the cylinder head, and the cooling water provided with an exhaust heat recovery device, a heater and a sub-water pump outside the internal combustion engine Applied to a cooling device comprising a sub-loop path that is a path,
The main loop path branches into a first path that passes through the radiator and the thermostat outside the internal combustion engine, and a second path that bypasses the radiator and the thermostat and includes a part of the sub-loop path. ,
The sub-loop path is provided with a bypass path that bypasses the heater and closes a short loop path including the sub-water pump and the exhaust heat recovery device, and a switching valve that opens and closes the bypass path. Is provided,
Stop processing for stopping the main water pump on condition that the temperature of the internal combustion engine is equal to or lower than a predetermined temperature;
When the temperature of the internal combustion engine is equal to or lower than the predetermined temperature and the sub-water pump is in a driving state, the temperature rise rate of the cooling water in the closed state of the switching valve and in the opened state of the switching valve A control device for a cooling device that executes a determination process for determining whether or not the thermostat is open and stuck abnormally based on a comparison between a difference between the temperature increase rate of the cooling water and a threshold value.

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